In the early days of discovery of carbon nanotubes, it was expected that the side wall thereof is low in chemical reactivity similar to graphene sheets. But, at present, similar to fullerenes, there are reported various reactions with a reaction reagent of every kind.
It is also reported that by chemically functionalized carbon nanotubes, dispersibility is enhanced, or electrical resistance increases, and functionalization of the side wall greatly changes dispersibility or electronic properties of the carbon nanotubes.
Specifically, for example, for the purpose of minimizing influences given to a conjugated system by the addition to the side wall, there is made an attempt to introduce a dendrimer having a polyfunctional group introduced thereinto into the carbon nanotube side wall. Also, it is known, too that when an organosilicon substituent is introduced into the side wall, field emission properties of carbon nanotubes are enhanced, or n-type field effect transistor properties are revealed (Non-Patent Documents 2 and 3). In this way, molecular transformation by functionalization of carbon nanotubes is important in controlling properties of the carbon nanotubes.
In such chemical modification (functionalization) of carbon nanotubes, as a method of introducing an alkyl group into the carbon nanotube side wall, there are known a method of allowing single-walled carbon nanotubes to react with an alkyllithium or an alkyl Grignard reagent (Non-Patent Document 1); and a method of forming a reductive mixture with an alkali metal in anhydrous liquid ammonia and then allowing it to react by the addition of an organohalogen compound (Patent Document 1).    [Non-Patent Document 1] J. Am. Chem. Soc., 2006, 128, 6683    [Non-Patent Document 2] Chem. Mater., Vol. 18, No. 18, 2006, 4205 to 4208    [Non-Patent Document 3] Journal of Physics and Chemistry of Solids, 69 (2008), 1206 to 1208    [Patent Document 1] JP-T-2007-530400